ISIS Says No. 2 Leader Abu Muhammad al-Adnani Is Dead

Al-Adnani was at the top of the U.S. government's kill list of ISIS leaders

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ISIS' second-in-command, Abu Muhammad al-Adnani, is dead, according to the media arm of the terrorist organization, NBC News reported.

The circumstances of Abu Muhammad al-Adnani's death in Aleppo, Syria, have not been confirmed. Officials in Washington — who had put out a $5 million reward for al-Adnani — had no immediate comment.

The 37-year-old Syrian, who was ISIS' director of external investigations and main spokesman, is best known for issuing an edict for lone wolves to kill Westerners in September 2014.

He was at the top of the U.S. government's kill list of ISIS leaders, senior American military and intelligence officials told NBC News in December. The U.S. wanted al-Adnani dead because he was considered the author of the strategy of wanton murder that has left more than 500 dead in attacks around the world since October 10 — and apparently helped inspire last year's massacre in San Bernardino.